1. Field of the Invention
The present invention relates to a seat cushion structure for use in a vehicle front seat.
2. Background Information
A seat cushion for use in a front seat generally includes: a cushion portion, which is formed by a cushion pad on which an occupant is seated; and, a cushion frame, which extends around the outer-lower periphery of the cushion portion so as to form a frame member of the seat cushion. In addition, the cushion frame is provided with several different springs, which span the cushion frame in order to increase cushion-ability of the seat cushion. For one example of this structure, reference is made to Japanese Utility Model Application Laid-Open No. 63-29460.
FIG. 19 illustrates a seat cushion structure disclosed in the above application, which includes sinusoidal springs 200 and a pair of compression-coiled springs 202. The sinusoidal springs 200 span substantially the entire underside of a seat cushion 204. The compression-coiled springs 202 are positioned at a point corresponding to the hip joint of an occupant who is seated on the seat cushion (This position will hereinafter be referred to as a "hip point.")
In a seat cushion structure of this type, however, the different types of springs the sinusoidal spring 200 and the compression-coiled spring 202 in the above case are arranged in an intricate manner. Accordingly, problems with such a spring arrangement lie in that it is difficult to identify how each of the springs again, the sinusoidal spring 200 or the compression-coiled spring 202 in the above case exercises a cushion-ability effect on the entire seat cushion 204, and thus tuning (i.e., adjustment) of these springs is difficult to carry out.